Download Anja Engel, Alfred Wegener Institute for Polar and Marine Research

Earth Science / Geosciences / Environment
Planning Group Members: Takeshi Kakegawa and Claudio Richter
CO2 and Climate Change: Past – Present – Future
Speaker:
Anja Engel, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven
The sensitivity of the biological pump to changing CO2 in the ocean: What can we learn
from present day experiments?
There is now global awareness that human activities are responsible for increasing
atmospheric CO2 concentrations to a level higher than it’s ever been in the last 20 million
years. This awareness raises the need for a better understanding of the complex feedback
mechanisms between global climate and biogeochemical processes. Although tiny in size,
marine phytoplankton play a large role in the global carbon cycle, because each year they
remove about 45 Gt of inorganic carbon from the upper ocean during growth and redirect a
significant fraction to the ocean’s interior. This biological sequestration of carbon promotes
net uptake of the greenhouse gas CO2 from the atmosphere and is referred to as the ‘biological
pump’. Because CO2 and carbonate ions are substrates in metabolic processes, such as
photosynthesis and calcification, changes in their availability affect the physiology of cells
and the stoichiometry of metabolic products. The degree to which phytoplankton species can
tolerate changes of the carbonate system, and the extent to which the biological response may
affect the efficiency of the biological pump is still unknown. Therewith future atmospheric
CO2 concentration is difficult to predict. One approach for examining the response of marine
phytoplankton to changing CO2 concentrations is the use of perturbation experiments with
contemporary species. This lecture will present recent studies on CO2 effects on biological
processes from the organism to ecosystem level and will discuss the prospects and limits of
present day experiments for understanding the variability of the biological pump of the past,
present, and future.
Further readings:
Barker, S., J. A. Higgins, and H. Elderfield. 2003. The future of the carbon cycle: review, calcification response,
ballast and feedback on athmospheric CO2. Philosophical Transactions of the Royal Society of London
Series A361. 1810: 197-1999.
Hays, G. C., A. J. Richardson and C. Robinson. 2005 Climate change and marine plankton.
Trends in Ecology and Evolution 20 (6): 337-344.
Riebesell, U. 2004. Effects of CO2 enrichment on Marine Phytoplankton. Journal of Oceanography 60:719-729.
Web addresses:
www.imber.info
www.ipcc.ch